1). Field of the Invention
This invention relates to an interposer and a method of constructing an interposer.
2). Discussion of Related Art
Integrated circuits are formed on semiconductor wafers. The wafers are then sawed (or “singulated” or “diced”) into microelectronic dies, also known as semiconductor chips, with each chip carrying a respective integrated circuit. Each semiconductor chip is then mounted to a package, or carrier, substrate, thereby forming a semiconductor package. Often the packages are temporarily connected to test sockets so that the integrated circuit can be tested before it is sold. The package is then mounted to a printed circuit board, which may then be installed into a computing system.
Additional substrates, called interposers, are often used to ensure the electrical connection between the test socket and the package, as well as between the printed circuit board and the package.
Such an interposer typically has a substrate with “via holes” therethrough and “vias” within the via holes to electrically connect the package to either the test socket or the printed circuit board. The process of manufacturing interposers is difficult and expensive because numerous steps are required to create the via holes and vias, as each via hole must be drilled through the substrate and the vias must be electroplated through the via holes. The via holes are very small, and thus, the drilling is very difficult and time consuming. Additionally, the accuracy of the drilling is very difficult to control when drilling the via holes at small pitches. Furthermore, the vias do not maximize the flow of electricity and heat as the vias are cylindrically shaped with a space extending therethough.